Dual-flow turbine engine equipped with a thrust reversal system and a device for restricting the annular channel for the ejection of cold gases, and a restriction device equipping such a turbine engine

A turbine engine of the dual-flow type, comprising:

• a central generator (1) for channelling a jet of hot gas, and a pipe (2) disposed around the central generator (1) in such a way as to define an annular by-pass duct (3), for channelling a jet of relatively cold gas, the said pipe itself being surrounded by a fairing (4),
• a thrust reversal system with swing doors (5) disposed in line with the pipe (2),
• at least one device for restricting the annular by-pass duct (3) consisting of a fitting (7) forming a seat (9) and a shutter (8) the shape of which is adapted for being housed inside the seat (9) of the fitting (7), the said shutter being borne by a shaft (23) pivoting with respect to the fitting (7) and mounted so as to project with respect to the said shaft, each of the said at least one restriction devices being positioned in a cutout formed in the pipe (2), in such a way that the pivot axis (23) extends substantially transversely with respect to the longitudinal axis of the turbine engine, downstream of the shutter (8) with respect to the direction of ejection of the gases, and the fitting (7) being sealingly fixed to the pipe (2),
• pivoting means (24-29) for each shutter (8), arranged so as to cause it to pivot between two extreme positions:
• an open position in which the said shutter obstructs a section of the annular by-pass duct (3), and a closed position in which the shutter (8) is housed inside the associated seat (9), and in which it has the same profile as the internal face of the pipe (2),
• in which turbine engine:
• sealing means (14, 15) are disposed between the shutter (8) and the seat (9) of each restriction device, adapted for defining at least one airtight chamber between the said shutter and seat, in the closed position of the shutter, each seat (9) having, in line with each of the chambers, at least one communication orifice (18) between the chamber and the space between the pipe (2) and the fairing (4), so as to subject the shutter (8) to an overpressure force F suitable for keeping it clamped in its seat (9), and such that:
• F=S.times.(Pc-Pe)
• where:
• S is the total surface area of the shutter (8) delimited by sealing means (14, 15),
• Pc is the pressure in the annular by-pass duct (3),
• and
• Pe is the pressure in the chamber which, under steady operating conditions, corresponds to the pressure in the space between pipe (2) and fairing (4), that is to say the external pressure,
• elastic means (21) are arranged so as to act on each shutter (8) in such a way as to produce an initial release of the said shutter from its closed position, when the overpressure force F falls below a predetermined threshold value corresponding to a slowed operating speed of the turbine engine.